Succeeding to the previous reports, a comparative study on Ca balance during pregnancy and non-pregnancy was performed with albino rats, and Ca contents of the hard tissues of the mother rats immediately after their deliveries were investigated. The amounts of Ca contents of the control, high-and low-Ca group diet were 204, 961 and 29mg% respectively.
(1) Ca balances of the three groups were all positive during the pregnancy and the non-pregnancy, and therefore it seemed that the high-and low-Ca group showed good adaptation.
(2) The ratios of the amount of ash in defatted dried bones of three groups were more than fifty per cent, and were in normal range.
(3) Although Ca balances of low Ca group were positive, but from the results of the previous reports, it does not seems always to show the best physical condition.
(4) During the pregnancy, it is necessary to take a considerable amount of Ca, as much amount as which makes excretion in urine more than during non-pregnancy. And it is necessary to contain Ca 200mg% in the diet.